1. Field of the Invention
The present invention relates to a disc recorder for recording information, which is provided with a plurality of recording/reproducing channels and is capable of performing recording/reproducing operations through two or more channels in parallel each other.
2. Description of the Related Art
Disc recorders for recording information such as magnetic disc recorders, optical disc recorders and the like are widely used in recent years.
Among these disc recorders for recording information, a disc recorder which is provided with a plurality of disc faces for recording information and recording/reproducing heads arranged to confront these disc faces, is well known.
FIG. 1 is a block diagram showing a first example of a conventional magnetic disc recorder, and FIG. 2 is an explanatory diagram for explaining a system for recording information in the recorder shown in FIG. 1. Further, FIG. 6 is an explanatory diagram for explaining a format for recording/reproducing information in the recorders shown in FIG. 1 and FIG. 5 which will described later.
As shown in FIG. 1, a magnetic disc recorder 11 of the first conventional example is composed of a spindle 3, a set of five magnetic discs 2-1 to 2-5 designated generally as 2, and a disc face (0) which is an upper face of the uppermost disc 2-1, is referred to as 2.sub.0, a disc face (1) which is a lower face thereof is referred to as 2.sub.1, a disc face (2) which is an upper face of the second disc 2-2 is referred to as 2.sub.2, and the number is increased in consecutive order thereafter, and a disc face (8) which is an upper face of the lowermost disc 2-5 is referred to as 2.sub.8 and a disc face (9) which is a lower face thereof is referred to as 2.sub.9 fixed coaxially to the spindle 3 at equal intervals, a spindle motor 4 for rotating the spindle 3, thus the discs 2 are rotated in a CAV (constant angular velocity) system, magnetic heads 5.sub.0 to 5.sub.9 respectively confront disc faces (0) to (9) i.e. 2.sub.0 to 2.sub.9, a total of 10 heads 5.sub.0 to 5.sub.9 is designated generally as 5, and those 10 heads are suspended by respective arms, respective proximal ends thereof are coupled together to move as a unitary component in the radial direction of the discs 2, the magnetic heads 5.sub.0 to 5.sub.9 are electrically and respectively connected to a head selecting circuit 19 which selects one of these heads 5.sub.0 to 5.sub.8 and cause the selected head to perform a recording/reproducing operation, a recording/reproducing circuit 16 for controlling the recording/reproducing operation of the selected head, a tracking servo circuit 7 connected to the head 5.sub.9 for positioning the magnetic heads 5 in the radial direction of the discs 2 by driving an actuator (not shown) based on a tracking servo signal obtained from the head 5.sub.9 which detects a tracking servo signal prerecorded on a servo track on the lowermost disc face 2.sub.9, the tracking servo circuit 7, the recording/reproducing circuit 16 and the head selecting circuit 19 are connected respectively to a control circuit 18 which controls operations of these connected circuits in response to instructions from a host system (not shown) or the like.
In a format for recording/reproducing of information on these disc faces 2.sub.0 to 2.sub.8, each track is constituted of 52 sectors from a sector (0) to a sector (51), and one logical block (hereinafter abbreviated as a block) which is an information unit recorded on or reproduced from one each sector, is constituted of a control signal region including address mark signals, synchronizing signals, a signal for error correction and the like and a data region where user data are recorded/reproduced as shown in FIG. 6. Since the capacity "S" of this control signal region is 87 bytes and the capacity "D" of the data region is 512 bytes, one block includes 599 bytes.
As shown in FIG. 2, in an information recording system according to this first example of conventional magnetic disc recorder 11, when the heads 5 are positioned on a track (n), the head 5.sub.0 records or reproduces an information in the blocks (0), (1) and (2) on or from the track (n) of the disc face (0) in the order of sectors (0), (1) and (2) respectively. After a block (51) is recorded or reproduced on or from the last sector (51), the head 5.sub.1 records/reproduces an information in the blocks (0), (1) and (2) on/from the track (n) of the disc face (1) in the order of sectors (0), (1) and (2) respectively.
Accordingly, the information is recorded/reproduced in series in the unit of blocks on the track of the designated disc face. This conventional system of recorder 11 has a drawback of slow recording/reproducing speed due to the series recording/reproducing operations by a single head selected from the magnetic heads 5.sub.0 to 5.sub.8.
On a second example of conventional magnetic disc recorder, such drawback is improved where recording/reproducing operations are performed with two or more heads operating in parallel. Next, this type of magnetic disc recorder will be described as the second example being compared with the first example of recorder 11.
FIG. 3 is a block diagram showing the second example of a conventional magnetic disc recorder, and FIG. 4 is an explanatory diagram for explaining an information recording system in the recorder shown in FIG. 3.
As shown in FIG. 3, a magnetic disc recorder 21 in a second example is composed of the above mentioned magnetic discs 2, the spindle 3, the spindle motor 4, the magnetic heads 5, recording/reproducing circuits 6.sub.0 to 6.sub.8 (a total of 9 circuits are referred to generally as 6), the tracking servo circuit 7, and a control circuit 28.
The heads 5.sub.0 to 5.sub.8 are connected respectively to the recording/reproducing circuits 6.sub.0 to 6.sub.8 which control recording/reproducing operations of these heads 5.sub.0 to 5.sub.8, and the tracking servo circuit 7, and the recording/reproducing circuits 6 are connected respectively to the control circuit 28 which controls operations of these connected circuits in response to instructions from a host system (not shown) or the like. Description of similar parts to those in the recorder 11 of the first conventional example will be omitted here.
In an information recording system in the magnetic disc recorder 21, as shown in FIG. 4, when the magnetic heads 5 are positioned on the track (n), the heads 5.sub.0 to 5.sub.8 record or reproduce in parallel operation the control signal regions of one block explained with reference to FIG. 6 on or from the disc faces (0) to (8) i.e. 2.sub.0 to 2.sub.8 respectively. Thereafter, the first byte (0) in the data region including 512 bytes is divided into a bit (0) to a bit (7) and is added with a parity bit (P) to form a 9-bit signal which is recorded or reproduced on or from the disc faces (0) to (8) simultaneously in parallel operation, subsequently, the byte (1) divided into a bit (0) to a bit (7), is added with a parity bit (P) and is recorded in parallel operation.
Recording/reproducing in this manner continues up to the byte (511) so as to complete the block (0), and similarly, the parallel operation (simultaneous recording or reproduction by the heads 5.sub.0 to 5.sub.8) progresses with the blocks (1) and (2). Namely, data of 9 bits including a parity bit (P) are recorded/reproduced in parallel operation on the designated respective tracks on the 9 faces of the discs 2. Thus, a capacity of respective data regions in this case becomes 1/8 ("D"/8=64 bytes) per disc face of the case of the first conventional example, and one block includes 151 bytes.times.9=1,359 bytes.
This makes the second example disc recorder deficient in formatting i.e. it requires to provide the control signal region on each of the disc faces where the one block is comprised of 9 disc faces, this means poor surface utilization.
Accordingly it is an object of the present invention to provide a disc recorder for recording information in which a recording/reproducing speed is high and a format efficiency is improved.